162 Mr. M. A. C. Hiiiton o?i the 



Explanation of Figures, 

 a, right upper molars ; b, left lower molars. 



-Eothenomys melanogaster confinii, subsp. n. Type c? . B.M. 



No. 22.12.1.1. Original No. 173. Kiu-chiang-Salween divide 



{Forrest). X 8. 

 -Eothenomys Jidelis, sp. n. Type $. B.M. No. 22.12.1.8. 



Original No. 455. Lichiang Range, Yunnan (i'orres^V X 7'5. 

 -Eothenomys melanogaster colurnus, Thos. $. B.M. No. 



98.11.1.27. Kuatun {J. de la Touche). x 7. 

 -Eothenomys olitor, Thos. (4 h, right lower molars). $ . B.M. 



No. 11.9.8.123. Chao-tung-fu, Yunnan {M. P. Anderson). 



X 8. 

 -Eothenomys proditor, sp. n. Tj^pe S - B.M. No. 22.12.1.10. 



Original No. 9. LichiangRanae, Yunnan (Fon-cs;^). X 7*5. 

 -Anteliomys wardi, Thos. $ . B.M. No. 22.12.1.30. Original 



No. 213. Mekong-Salween divide (Forrest), x 8. 

 -Caryomys inez, Thos. S- B.M. No. 9.1.1.184. Shensi 



{Malcobn Anderson). X 8. 

 -Neodon sikimetisis, Hodgson. B.M. No. 15.9.1.218. Lachen, 



Sikkim (Bombay Nat. Hist. Soc). X 8. 

 -Neodon forresti, sp. n. Type S ■ B.M. No. 22.12.1.35. Original 



No. 145. Mekong- Yangtze divide (Fondest). X 9. 

 -Neodon irene, Thos. $, B.M. No. 12.3.18.13. A-tun-tsi, 



N.W. Yunnan [F. K Ward). X 8. 

 -Neodon carruthersi, Thos. $. B.M. No. 9.4.3.93. Hissar 



Mts., Turkestan {D. Carrvthers). X 8. 

 -Neodon oniscus,T)ioQ. Type (5^. B.M. No. 11,11.1.3. KanBu 



[M. Anderson). X 8*5. 

 -Microtus calamorwn superus, Thos. cJ • B.M. No. 11.6.1.46. 



Shen-Si {M. Anderson). X 8. 

 -Microtus clarhei, sp. n. Type $ . B.M. No. 22.12.1.46. Ori- 

 ginal No. 175. Kiu-chiang-Salween divide {Forrest), x 8. 



XIII.— T^e Dental Formula of the Muridse, with especial 

 reference to the " mp. 4 Theory ^ By Martin A. C. 



HiNTON. 



(Published by permission of the Trustees of the British Museum.) 



While working out a large collection together recently, 

 Mr. Oldfield Thomas and I thought we ought to take the 

 opportunity of expressing an opinion as to the notation that 

 should be used for the three cheek-teeth of the Muridse, 

 apropos the formula used for certain voles by Mr. R. Kellogg*. 

 Although Mr. Kellogg does not say how far the formula he 



* Kellogg, "A Study of the Californian Forms of the Microtus 

 montanus Group of Meadow-Mice," Univ. Oal. Tubl. Zool. xxi. p. 245 

 (1922). 



Fig. 



1. 



Fig. 



2, 



Fig. 



3. 



Fig. 



4. 



Fig. 



5. 



Fig. 



6. 



Fig. 



7. 



Fig. 



8. 



Fig. 



9. 



Fig. 



10. 



Fig. 



11. 



Fig. 



12. 



Fig. 



13. 



Fig. 



14, 



